A gamma camera is a system used in the medical subspecialty of nuclear medicine. The gamma camera has the ability to detect photons from radionuclide or radiopharmaceutical. The radiopharmaceutical is administered into the body and it will then distribute in accordance with body's anatomy, physiology and any pathologic conditions. Planar images from a gamma camera are obtained from a single gamma camera position with the use of a collimator, such that the directionality of the photon can be inferred. Parallel collimators provide directionality and the image size is equivalent to the object size. Pinhole collimators are commonly used to image small objects such as the thyroid gland, such that a magnified image can be obtained. A two-dimensional image is produced providing diagnostic information.
A Single Photon Emission Computed Tomography (SPECT) system is also used in nuclear medicine. Once again, the radiopharmaceutical is administered and it distributes within the body. The SPECT system acquired image data using a gamma camera from multiple locations and processes the images such that a three-dimensional data set can be obtained. SPECT images can be overlaid with Computed Tomography (CT) to enhance detection, specifically improving localization within the body.
A Positron Emission Tomography (PET) system is also used in nuclear medicine. The radiopharmaceutical is administered and it distributes throughout the body. The radiopharmaceuticals used in this procedure emit positrons. The positrons travel a short distance in the body and then annihilates with an electron and produces two 511 keV photons, which are emitted approximately 180 degrees apart as shown in FIG. 1.